The present invention relates to fuel loading systems, and more particularly, to an apparatus and positive method for indicating the proper precheck operability of fuel level control valves of a fuel receiving system.
The fuel loading system for aircraft, and particularly military aircraft, includes fuel level control valves, or check valves, for controlling the received amount of fuel upon refueling of the airplane by ground equipment. The existing method used by ground maintenance personnel to verify the fueling operation of the fuel level control valve is to observe "hose kicks" which results in the hose stiffening when fuel flow is stopped by the fuel level control valves upon achieving a predetermined level of fuel in the receiving system. In systems wherein a plurality of airplanes are simultaneously fueled from a common fuel supply source, such as a tank truck, the hose kick resulting from adequate fueling of one airplane is attenuated by connection of other hoses simultaneously fueling other airplanes. In such a case, improper operation of a fuel level control valve will be difficult to observe with the result that the fuel tank of the respective airplane will overflow with the excess fuel exiting through an overflow vent thereby resulting in fuel spillage onto the ground or a flight deck of an aircraft carrier. Such a spillage presents a substantial safety hazard.
Additionally, it is not uncommon for a fuel level control valve to only partially close at the proper refueling cut-off point. In such an event, a "hose kick" will result, however, fuel flow into the airplane fuel tank may not be completely shut-off and continues at a reduced rate with resulting overflow spillage and safety hazard conditions described hereinabove. Accordingly, it is desirable to provide an apparatus and method for checking the proper operability of the fuel control valves prior to delivery of fuel.